1. Field of This Invention
This invention relates to a process for the production of certain 2-amino-benzothiazoles.
2. Prior Art
German published application no. 1,916,599 discloses producing 2-amino-6-methoxy-benzothiazole by reaction of a halogen or sulfur halide as a cyclization agent with p-methoxy phenylthiourea in the presence of an inert solvent. The process is characterized in that a pH value of 2.6 to 3.4 is obtained in an aqueous solution of the salt of the 2-amino-6-methoxy-benzothiazole at a temperature between 40.degree. and 85.degree. C. and in that the precipitated impurities are separated.
4- AND 6-SUBSTITUTED 2-AMINO-BENZOTHIAZOLES ARE PRODUCED BY CYCLIZATION OF 2- AND 4-SUBSTITUTED N-arylthiourea using bromine, sulfurylchloride, chlorine, SCl.sub.2 or SbCl.sub.5 in chloroform, chlorobenzene, ethylene, dichloride or nitrobenzene. (See J. Chem. Soc. (C), 1969, p. 268.)
The known processes have the disadvantages of requiring relatively large quantities of solvent, from which the end product must again be separated after the reaction is completed. The reaction time, moreover, is very long in the case of the known processes.